There are a myriad of motors which are commercially available. The motors are usually driven by combustible fuels, electricity, solar energy, or a combination of any one or more of these sources of energy. Each energy source has its own drawbacks. For example, most combustible fuels when burnt produce gases which are harmful to the environment. Furthermore, if the fuel is not completely burnt the unburnt fuel can be exhausted and also adversely affect the environment.
Alternative sources of energy, such as photovoltaic generated electricity has been used for driving motors. Electricity in remote areas is somewhat restricted in that the storage of sufficient quantities of electrical energy in, for example, batteries takes up large amounts of space, is relatively expensive, and can also be extremely heavy. Solar energy is inherently restricted for at least the following reasons. Solar energy is only available during sunlight hours and may vary in intensity depending on the season of the year. Particularly cold areas of the world may never lend themselves to solar energy as an alternative energy supply. Furthermore, photovoltaic generated electricity is relatively expensive to produce.
When solar energy has been used as an energy source it is usually absorbed on a collector panel. The absorbed heat from the panel is then exchanged with a fluid, in the form of specific heat, and ultimately used in a variety of ways to drive a motor or generator. Relatively small quantities of energy can be stored in the form of specific heat and solar powered electric motors, for example, have relatively little power. Furthermore, solar energy when used to drive a motor or generator is limited by the cost of photovoltaic cells and storage batteries.